Is there a Simplify Curves addon for Blender 2.80?
Select your keyframes on graph editor.
Press "o" Select SMOOTH KEYS. That should "simplify" a little bit better your curves.
I remember the function "simplify curve" is available for grease pencil, but I don´t remember seeing it elsewhere. Please paste a screen capture.

I hope this works for you. If it does, please vote me up and mark me on the checkbox to the left side of this answer. 
Thank you.